AEVA Homepage
Forum Home Forum Home > Technical Discussion > Electric motors and controllers
  New Posts New Posts RSS Feed - 2 pole / 4 pole differences
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

2 pole / 4 pole differences

 Post Reply Post Reply Page  <123>
Author
Message
woody View Drop Down
AEVA Member
AEVA Member
Avatar

Joined: 29 June 2008
Location: Mt Colah
Status: Offline
Points: 1761
Post Options Post Options   Thanks (0) Thanks(0)   Quote woody Quote  Post ReplyReply Direct Link To This Post Posted: 12 September 2009 at 9:21pm
Originally posted by Sparky Brother Sparky Brother wrote:

Originally posted by acmotor acmotor wrote:

TJ, the pic won't download.....

Ah, fresh air, no more 2 pole talk !!!


Hi all

I have recently done lots of thinking how to go around my 2 pole (sorry acmotor ) motor problems and basically got through anything one can come up with; Keeping the car`s gear box? Nah! Too much labour if I want to do it right and install a working clutch.

Get an auto GB, get rid of the torque converter and actuate the clutches by a separate pump/controls or use electrical actuators. Too much labour again!

Not to mention the crazy ideas on hydraulic Pump/Motor set up - too dirty!

All right just to warm Johny and Woody`s hearts - Yesterday I spoke to someone at WEG (my 2P one is WEG) about a possible rewinding to 4 pole. Unfortunately to me this guy was either too lasy to think or not that knowledgible so the answer was more like - Mmm? I don`t think there will be any benefit out of that. At least he gave me the phone of a guy from their distributor company that might know the stuff better


I more hopeful that the 2 pole - 4 pole rewind/wire is possible now.

Originally posted by Sparky Brother Sparky Brother wrote:


Apart from that I spoke to my good friend Lona from Mark Air (they have account with ABB) to get me a Quote on a M3AA112MB3GAA132 316-ADE 15 kW 4 pole aluminium motor and hopefully it will be able to afford it.

I got a quote (thanks again to Weber) for a 132-316-HSE (h = foot + flange, s = star IE 400v star/ 230 delta) it was $1000 delivered.
Originally posted by Sparky Brother Sparky Brother wrote:


Meanwhile today I crunched some numbers just for the fun of it and came to the "brilliant" conclusion that
since the torque of a motor is derived from this formula: T= (60 x watts):(2 x 3.14 x RPM) If I forget for a minute about the limitations of the controller and probably other factors it would be theoretically possible to squeeze out 95.5Nm @ 400V 25 Hz off the same 2P motor that normally gives you 47.7Nm @ 50 Hz.

that formula is also expressed as kW = Nm * RPM / 9550 and is just the relationship between torque, rpm and power. Your controller puts out amps and Volts which are required for torque and speed, but a 20kW controller won't put out 20000 amps at 1 volt, nor will a normal 20kW motor put out 200000 Nm at 1rpm, unfortunately.
Originally posted by Sparky Brother Sparky Brother wrote:


Now I just wander since the enemy here will be the Inductive reactance of the windings would it be possible to engineer a bank of capacitors that gets switched on at certain frequency reducing the Inductive reactance and producing more torque at pull out.

This is probably another not well supported theory of mine. Any way anything you guys think about it, shoot it! This is my way of learning



Edit

Yes I Realize 95.5 Nm is not enough this is why I came up with the crazy theory about the interim PF correction


You can feed more volts and amps at low rpm to get more torque (Danfoss torque boost) but this is at the expense of efficiency and you need to have spare amps to do it.

I don't think capacitors between motor and controller will help.
Repost to your feroza thread with motor and controller specs an batteries and I'll run some numbers if Johny doesn't beat me to it :-)
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
Back to Top
Squiggles View Drop Down
Senior Member
Senior Member


Joined: 21 April 2009
Location: Newcastle NSW
Status: Offline
Points: 765
Post Options Post Options   Thanks (0) Thanks(0)   Quote Squiggles Quote  Post ReplyReply Direct Link To This Post Posted: 12 September 2009 at 9:28pm
I wouldn't dismiss the PF correction idea straight away, there may be some merit. It used to be reasonably common for PF correction to be installed in factories with lots of induction machines, must have been a reason. Mind you it was of more interest to the electricity supplier than the factory, efficiency of transmission system etc.....is there an electrical engineer in the house?
Back to Top
coulomb View Drop Down
Senior Member
Senior Member
Avatar

Joined: 22 January 2009
Location: Brisbane
Status: Offline
Points: 2765
Post Options Post Options   Thanks (0) Thanks(0)   Quote coulomb Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2009 at 7:30am
Originally posted by Squiggles Squiggles wrote:

I wouldn't dismiss the PF correction idea straight away, there may be some merit. It used to be reasonably common for PF correction to be installed in factories with lots of induction machines, must have been a reason. Mind you it was of more interest to the electricity supplier than the factory

Low power factor is a nuisance for factories because it means that the cables, breakers, distribution transformers etc get hotter for no particularly good benefit. It gets expensive enough at the power distribution level that factories are forced to make their loads better than a certain mandated power factor. (Edit: they do this by putting capacitors across phases or from phases to neutral). But this has nothing to do with the performance of the motors.

The motor needs the reactance to cause it to draw reactive ("imaginary") power; it's basically the reactive power that energises the field. So reactance isn't an "enemy" here. To get more torque, you need more reactive power, so you need to increase the V/f as mentioned earlier, or increase the reactance (e.g. add more turns to all the stator windings).

Think about what reactance is: it's inductance in the windings. Inductors store power in the magnetic field at one part of the cycle, and return it at another part of the cycle (less losses). An ideal inductor just creates and collapses a magnetic field. It draws power from the mains/inverter to create the field, and sends the same energy back to the mains/inverter when the field collapses.

In most inductors, the magnetic field isn't used in any way, other than to return power to the mains or inverter. But in an induction motor, the magnetic field from this inductance is the field that is used to generate torque. Just as with a permanent magnet, the field isn't "used up" by this process, it just has to "be there".

An induction motor will therefore always have a lagging (inductive) power factor. Factories add capacitors across the mains to correct this power factor, so that most of the power for energising the motors' fields will come from the capacitors, and most of the energy coming back from the collapsing fields will go to the capacitors. So the reactive current will flow between the motors' inductance and the capacitors, and not through the main breakers and distribution transformers.

With an inductor, E = L. dI/dt or dI/dt = E/L,

where E is the applied EMF (winding voltage), L is the inductance (a constant depending on the number of turns etc), and dI/dt is the rate of change of current. You need more dI/dt for higher frequency applied to the windings (the current has to change faster to reach the same peak and therefore RMS value), so that's why you need a certain V/f to "energise the field".

Attempting to somehow "cancel" the windings' inductance would be counter productive. Adding capacitors across the motor would improve the power factor, but would "short circuit" the much faster PWM pulses. You'd very likely blow up the controller. Adding capacitors across the AC input of a factory motor would improve the power factor, and as Squiggles notes this is a common, even mandated practice. But it would have no effect on the torque of the motor there, except perhaps to reduce losses on the cables feeding the motor (hence improving the torque a little).

I hope this helps visualise what's going on. Writing this has helped me!

Edited by coulomb - 13 September 2009 at 7:34am
Working with Weber on finishing an electric MX-5
Back to Top
Sparky Brother View Drop Down
Groupie
Groupie


Joined: 29 March 2008
Location: Melbourne
Status: Offline
Points: 99
Post Options Post Options   Thanks (0) Thanks(0)   Quote Sparky Brother Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2009 at 8:35am
I feel so bad but yeah coulomb thanks for the educational session indeed. I really had the feeling I am missing something important. If it worked it would be the perfect Panacea for all our motor related dreams wouldn`t it?
Back to Top
Sparky Brother View Drop Down
Groupie
Groupie


Joined: 29 March 2008
Location: Melbourne
Status: Offline
Points: 99
Post Options Post Options   Thanks (0) Thanks(0)   Quote Sparky Brother Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2009 at 10:21am
Sorry woody and Squiggles. Somehow I was directed straight to coulombs message ignoring your ones.

Squiggles,

I am very much inclined to think in your direction of understanding as to why the distributors are so concerned about the PF correction.

I was just thinking. If we try to simplify things, our battery pack and the inverter could be represented as the power supply company that otherwise supplies power to our motor so the question is - why shouldn`t we be concerned about an active PF correction then?

Can anyone remind me please. Was there a relationship between the changing frequency and the PF? I am looking for it in my formulas sheet but I am unable to find it anywhere

Woody

If my connection gets me the price you got on this motor I think I will be pretty happy to have one of those beauties. Especially with the weight in mind I will be more than delighted to shed some 20 kilos off my original plan to use the 110kg Cast Iron body WEG

Re. my Feroza thread I am kind of unabe to find it my self. I might need to create one under Members Machines
Back to Top
coulomb View Drop Down
Senior Member
Senior Member
Avatar

Joined: 22 January 2009
Location: Brisbane
Status: Offline
Points: 2765
Post Options Post Options   Thanks (0) Thanks(0)   Quote coulomb Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2009 at 12:56pm
Originally posted by Sparky Brother Sparky Brother wrote:

If we try to simplify things, our battery pack and the inverter could be represented as the power supply company that otherwise supplies power to our motor so the question is - why shouldn't we be concerned about an active PF correction then?

You mean apart from the fact that it would blow up the controller? Actually, not much, it's a pretty good idea.

A typical induction motor has a power factor of 0.80 to 0.85. That means that 15-20% of the controller's output current capability is "wasted" providing field excitation. (At least it's not wasted as heat, as it is with a DC motor). But the inductance of the motor is needed as part of the Pulse Width Modulation and voltage translation (including regen).

But I think you could do something like this:



The inductors L1-L3 could be the bulky inductors you hoped to toss out from the front end of your controller, where they prevent PWM pulses from getting into the mains and radiating throughout the factory. The capacitors C1-C3 would be bulky and moderately expensive, but possibly not as expensive as extra silicon to provide 15-20% more current. I've never seen this done (but I don't have much to do with industrial setups), so I suspect the extra silicon might be easier, if not cheaper. TJ? Others?

So the idea is that the capacitors correct the power factor of the motor as seen by the controller, but L1-L3 provide the required inductance for the controller's PWMing. So now most of the current from the controller can be used for traction, instead of sharing the current limit between exciting the field and traction.

The downside is the bulk, weight, and expense of the extra passives (L1-L3 and C1-C3). The inductors from the input of our MX5's controller are something like 230 mm diameter, and weigh over 20 kg between them. That's over 35% of the weight of the controller. The capacitors would be lighter, but still bulky. They have to be unpolarised.

[ Edit 2011: I no longer think that this is viable. The capacitors reduce the power factor, but then the added inductors increase it again. Maybe by a little less. It likely would have little effect other than to increase the weight, cost, and bulk, and reduce efficiency. Also, the Ls and Cs would likely screw up the distribution of D and Q current, so the field excitation would likely be all wrong. Sigh. ]

Quote Can anyone remind me please. Was there a relationship between the changing frequency and the PF?

I believe that the power factor is independent of drive frequency. So one size should fit all as far as the values of L1-L3 and C1-C3 are concerned.

Edited by coulomb - 02 March 2014 at 5:56pm
Working with Weber on finishing an electric MX-5
Back to Top
Sparky Brother View Drop Down
Groupie
Groupie


Joined: 29 March 2008
Location: Melbourne
Status: Offline
Points: 99
Post Options Post Options   Thanks (0) Thanks(0)   Quote Sparky Brother Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2009 at 2:24pm
!5 even 20% more power to the motor?! You beauty!

Having in mind that I will most likely go for Direct Drive and lighter by 20 kg than the originally planned for the conversion motor what is some 20-30 kilos in inductors and capacitors? We must admit that 35% of the weight of the inverter in addition to the overall weight of the car is almost nothing compared to the opportunity to wipe off some at least 15% losses at the Motor.

Thanks for the neat diagram coulomb!
Back to Top
coulomb View Drop Down
Senior Member
Senior Member
Avatar

Joined: 22 January 2009
Location: Brisbane
Status: Offline
Points: 2765
Post Options Post Options   Thanks (0) Thanks(0)   Quote coulomb Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2009 at 5:02pm
Originally posted by Sparky Brother Sparky Brother wrote:

15 even 20% more power to the motor?! You beauty!

Bear in mind that that's only if you were controller limited before, so your controller just wouldn't deliver the current the motor needed for full torque.

It would be most useful (assuming that this idea works) if you really needed a controller between two available sizes, e.g. one was 10% too small, and the next one up is 50% dearer and 40% more current than you need, and won't fit or something. Then you could use the smaller inverter with the extra parts and get full torque (and probably hence full power) from the motor.

Of course, the Ls and Cs and their associated cables have their own losses, so even if the motor's power factor at full power was 0.80, you wouldn't get the full 20% extra.
Working with Weber on finishing an electric MX-5
Back to Top
weber View Drop Down
Senior Member
Senior Member
Avatar

Joined: 23 January 2009
Location: Brisbane
Status: Offline
Points: 1732
Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2009 at 10:15pm
I don't believe an induction motor designed as a 2-pole can be rewired as a 4-pole, or vice versa, without an enormous reduction power. Of course rewinding is not a problem.

Here are some diagrams that will hopefully explain why.



These diagrams are a kind of shorthand for stator windings, where we abstract things away to the point where a single straight line represents a coil, as if its end-windings could just hop directly from one coil-side to the other, ignoring the rotor and shaft.

I'm showing concentric windings here as an example. The 2-pole has coils spanning 13, 15 and 17 teeth while the 4-pole has coils spanning 7, 9 and 11 teeth.

If you rewire the 2-pole as a consequent 4-pole there's hardly anywhere for the consequent poles to form and we just end up having the two coils mostly cancelling each other out. With a consequent 4-pole being rewired as a 2-pole a lot of flux will be wasted taking a shortcut between the two widely separated windings. And in both cases the harmonics will be dreadful.

Another difference between 2-poles and 4-poles is shown by the ABB catalogs. In the 132-frame size a 2-pole typically has 70% of the peak torque of a 4-pole of the same weight. Not 50% as many people mistakenly assume.

And hence a 2-pole has 140% of the peak power of a 4-pole of the same weight. Woody's favourite 15 kW 4-pole does a little bit better than the average, but it is still outclassed on power by the 22 kW 2-pole that weighs only 3 kg more (95 kg to the 4-pole's 92 kg). I note that these two motors are the most powerful 2-pole and 4-pole respectively in the ABB 132-frames.

For some unknown reason the 22 kW 2-pole is far more expensive than the 15 kW 4-pole, but both may turn out to be vapourware.

But I note that if you are not going to have a gearbox then you definitely do not want a 2-pole induction motor.

[Edit: Added "induction" twice]

Edited by weber - 13 September 2009 at 10:27pm
Putting the finishing touches on Mexy the electric MX-5
Back to Top
Squiggles View Drop Down
Senior Member
Senior Member


Joined: 21 April 2009
Location: Newcastle NSW
Status: Offline
Points: 765
Post Options Post Options   Thanks (0) Thanks(0)   Quote Squiggles Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 6:10am
Originally posted by weber weber wrote:



If you rewire the 2-pole as a consequent 4-pole there's hardly anywhere for the consequent poles to form and we just end up having the two coils mostly cancelling each other out.


What is the advantage of consequent poles?
Why do the coils cancel each other?

Edit: forget this, I just looked at the diagrams again and they made sense this time....no coffee in system yet!!

Edited by Squiggles - 14 September 2009 at 6:12am
Back to Top
coulomb View Drop Down
Senior Member
Senior Member
Avatar

Joined: 22 January 2009
Location: Brisbane
Status: Offline
Points: 2765
Post Options Post Options   Thanks (0) Thanks(0)   Quote coulomb Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 8:44am
Originally posted by weber weber wrote:

... where we abstract things away to the point where a single straight line represents a coil, ...

I've confirmed with Weber that the short line segments around the circumference (yes, it's not actually a circle, it's a tri-deca-hexagon or whatever a 36-sided figure is called) are not meant to represent coils. It's an artefact of Excel's plotting facilities. So only the longer, non-circumferencial lines represent coils.

Edit: I tri two spel gooder

Edited by coulomb - 14 September 2009 at 8:46am
Working with Weber on finishing an electric MX-5
Back to Top
weber View Drop Down
Senior Member
Senior Member
Avatar

Joined: 23 January 2009
Location: Brisbane
Status: Offline
Points: 1732
Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 9:13am
Originally posted by Squiggles Squiggles wrote:

Originally posted by weber weber wrote:



If you rewire the 2-pole as a consequent 4-pole there's hardly anywhere for the consequent poles to form and we just end up having the two coils mostly cancelling each other out.


What is the advantage of consequent poles?
Why do the coils cancel each other?

Edit: forget this, I just looked at the diagrams again and they made sense this time....no coffee in system yet!!

Actually. Thanks for picking that up. I should have written "and we just end up having two groups-of-3-coils mostly cancelling each other out, in each phase."

I've been very lazy just using Excel to plot these. Ideally these diagrams would use one colour (black) for the stator iron (pseudo-circle) and 3 other colours (RGB) for the 3 different phases [Edit: was "3 windings"], and would have arrows on each coil (long-line) to show the different relative phasing between the 4-pole consequent and the 2-pole.

Or maybe remove all but one phase and show some curves representing "lines of flux".

Also could do the usual unrolled stator diagrams.

But I have to say I don't know for sure if concentric-wound 36 slot 2-poles are wound this way. I can't find anything that clearly confirms (or denies) this on the web. The theory just seems to tell me they ought to be wound this way (or something very like it, and unlike the 4-pole consequent).

Edited by weber - 14 September 2009 at 9:59pm
Putting the finishing touches on Mexy the electric MX-5
Back to Top
woody View Drop Down
AEVA Member
AEVA Member
Avatar

Joined: 29 June 2008
Location: Mt Colah
Status: Offline
Points: 1761
Post Options Post Options   Thanks (0) Thanks(0)   Quote woody Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 9:55am
[QUOTE=weber]
Here are some diagrams that will hopefully explain why.


[/QUOTE

I didn't know you'd ordered already :-) Bummer about the delays.

I guess I'd been thinking 4 pole consequent pole and 2 pole winding were the same, probably because of Dahlander.

Dahlander works a lot better efficiency-wise than I'd thought.

The more we find out, the more we need to.

cheers,
Woody
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
Back to Top
Johny View Drop Down
AEVA Member
AEVA Member
Avatar

Joined: 23 June 2008
Location: Melbourne
Status: Offline
Points: 3476
Post Options Post Options   Thanks (0) Thanks(0)   Quote Johny Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 11:15am
Originally posted by Sparky Brother Sparky Brother wrote:

Re. my Feroza thread I am kind of unabe to find it my self. I might need to create one under Members Machines

The only Feroza thread started was this one.
I will post some spreadsheet results there.
Back to Top
bga View Drop Down
Senior Member
Senior Member
Avatar

Joined: 01 September 2008
Location: Perth WA
Status: Offline
Points: 493
Post Options Post Options   Thanks (0) Thanks(0)   Quote bga Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 3:21pm
Does anybody ever wind motors concentrically? It looks like a lot of wasted copper around the ends of the stator.

Power factor: Why worry?
It's being driven by a PWM controller the whole idea of the controller is to manage the flux (magnetic field) in the motor via the efficient IGBTs and link capacitors.

The LC network between the controller and the motor is a low pass filter that'll reduce the harmonics at the motor. The drive makers usually reccomend this if the motor leads are long.
The controller needs certian minimum inductance to work properly. It can only cope with limited di/dt from the motor. Big and low voltage motors have low inductance compared to small and high voltage motors.

Power factor is an AC supply thing so that the factory power supply doesn't get upset by having all the current being drawn out of phase with the voltage -- its irrelevant in DC battery systems.

I would expect the 2 pole windings would be wider than 4 pole winding (span more slots).


Edited by bga - 14 September 2009 at 3:22pm
Back to Top
weber View Drop Down
Senior Member
Senior Member
Avatar

Joined: 23 January 2009
Location: Brisbane
Status: Offline
Points: 1732
Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 9:08pm
Yes. That's the important point, bga. No matter whether they are concentric, lap or wave wound, a 2-pole will have larger coil-spans than a 4-pole.

Concentric winding definitely is used commercially. Coulomb has taken apart a 7.5 kW 132-frame 4-pole and it has exactly the arrangement I've shown above, with coil spans of 7, 9 and 11 teeth. So the average span is 9 which is exactly what you want for a 36 slot 4-pole. 36/4 = 9.

Woody, it seems that Dahlander winding is a compromise between a 2-pole winding and a 4-pole consequent winding. There's no reason why efficiency should suffer under such a compromise (except possible the poor harmonics), but peak power for a given size or weight will be lower.

A Dahlander would presumably have coil spans intermediate beweeen those of a 2-pole and a 4-pole.

Here's a 36-slot winding scheme I found with concentric windings and no slot sharing (like the other two above) that looks kinda like a compromise between 2-pole and consequent 4-pole, although I seriously doubt that this is what is actually used in a Dahlander.



This Google book has some useful numbers on Dahlander "winding factors".
http://books.google.com.au/books?id=4-Kkj53fWTIC&lpg=PA234&dq=Dahlander&pg=PA234#v=onepage&q=Dahlander&f=false
Unfortunately the figure showing the actual winding layout is not part of the preview. But the text makes it sound as though you'd have a better result rewiring a consequent 4-pole as a 2-pole than the other way 'round. But that's probably not very useful.

I should also have said earlier that, even if you keep the gearbox, you can still use a 4-pole, provided you are willing to overvoltage and overspeed it by a factor two times greater than you would with a 2-pole. To do this, you need to have the 4-pole rewound for half the voltage of the 2-pole. You will then obtain about 1.4 times the peak power of a 2-pole of the same weight (note: not 2 times the peak power as some people assume).

[Edit: Clarified "power" -> "peak power" twice above]

Edited by weber - 14 September 2009 at 9:16pm
Putting the finishing touches on Mexy the electric MX-5
Back to Top
weber View Drop Down
Senior Member
Senior Member
Avatar

Joined: 23 January 2009
Location: Brisbane
Status: Offline
Points: 1732
Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 9:37pm
The only advantages I can see for consequent poles are
(a) You can do the Dahlander thing, and
(b) they are easier to wind.

There seems to be an incredible dearth of information about stator windings, and particularly diagrams of them, on the web. I said to Coulomb today that the information must be in books. You know, those old fashioned things made out of squashed wood pulp.

I think I just found the Mother Lode. And it costs about its weight in gold too AU$200.00). Liwschitz-Garick is the Author. Published in 1950.
http://www.amazon.com/Winding-Alternating-Current-Machines-Repairmen-Designers/dp/0911740031/ref=sr_1_1?ie=UTF8&s=books&qid=1252928318&sr=1-1

I'm not planning to buy one. But maybe someone could get it on interlibarry loan. I'm worried that the word "dahlander" doesn't occur in it, according to Google books, which only has a snippet view of it.
http://books.google.com.au/books?id=GU0hAAAAMAAJ&q=Liwschitz-Garik&dq=Liwschitz-Garik

[Edit: Fix where prudish forum interface had further corrupted my misspelling of the Author's name to "Liwsh*tz-Garick"]

Edited by weber - 13 October 2009 at 7:51am
Putting the finishing touches on Mexy the electric MX-5
Back to Top
vince View Drop Down
Groupie
Groupie


Joined: 31 May 2008
Location: On.Canada
Status: Offline
Points: 173
Post Options Post Options   Thanks (0) Thanks(0)   Quote vince Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 9:38pm
It seems to me that this thread winds up and just when something gets resolved oops another hair gets split.When and if this ever reaches a definite good,better,best,option someone please summarize for us hangers on.Thanks,one dizzy dude!
Back to Top
acmotor View Drop Down
AEVA Member
AEVA Member
Avatar

Joined: 25 April 2007
Location: Perth,Australia
Status: Offline
Points: 3796
Post Options Post Options   Thanks (0) Thanks(0)   Quote acmotor Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 9:44pm
Mmmm, so many assumptions there guys ! Some hard experimental data is required. A great effort to understand IM design though.

The 104V 4 pole at 6000RPM already demonstrates that peak power of 12x is there for the taking, yes duty cycle and maybe efficiency aside, it is real peak shaft power. The sort of thing an EV lusts after for those all important seconds !
You can do the same with 2 pole but the 12,000RPM may be the downside.


Also thinking, is it the consequent poles (and resulting dependence on stator iron) that works against a 4 pole ? Do any of the upmarket 4/8 poles like ACP or prius use consequent poles ?
The 104V motor was basket wound (4 separate coils per phase).
iMiEV, 61,052km in pure Electric and loving it !
Back to Top
woody View Drop Down
AEVA Member
AEVA Member
Avatar

Joined: 29 June 2008
Location: Mt Colah
Status: Offline
Points: 1761
Post Options Post Options   Thanks (0) Thanks(0)   Quote woody Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 9:50pm
Originally posted by vince vince wrote:

   It seems to me that this thread winds up and just when something gets resolved oops another hair gets split.When and if this ever reaches a definite good,better,best,option someone please summarize for us hangers on.Thanks,one dizzy dude!


Sorry Vince, I guess Weber, Johny, Coloumb, myself and others just like working stuff out.

Summary so far:
We found out more stuff we don't know about induction motors :-/
We don't think rewiring a 2 pole motor to 4 pole consequent will usually work.
Hopefully rewinding will.
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
Back to Top
vince View Drop Down
Groupie
Groupie


Joined: 31 May 2008
Location: On.Canada
Status: Offline
Points: 173
Post Options Post Options   Thanks (0) Thanks(0)   Quote vince Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2009 at 11:14pm
I would like to know (given that i had a small ac controller (say 500amp.72-120 volt and a 104volt motor,etc.) can i run this on 72,84,96 etc.volts?whats to be expected? Still striving for that bare bones efficiency/ transportation model.I apologise for how my mind works!
Thank you(s).

Edited by vince - 14 September 2009 at 11:16pm
Back to Top
vince View Drop Down
Groupie
Groupie


Joined: 31 May 2008
Location: On.Canada
Status: Offline
Points: 173
Post Options Post Options   Thanks (0) Thanks(0)   Quote vince Quote  Post ReplyReply Direct Link To This Post Posted: 15 September 2009 at 10:05pm
Would i be right in assuming that the above rewound 104v motor(in order to get the full benefits)would require a vfd and a much larger voltage to utilise the vfd?
Back to Top
acmotor View Drop Down
AEVA Member
AEVA Member
Avatar

Joined: 25 April 2007
Location: Perth,Australia
Status: Offline
Points: 3796
Post Options Post Options   Thanks (0) Thanks(0)   Quote acmotor Quote  Post ReplyReply Direct Link To This Post Posted: 15 September 2009 at 10:55pm
VFD needs higher voltage than standard 50Hz motor (x4) and more current.

Your are right. 104V is not about lowering the system voltage, it is about raising the performance (power to weight) well beyond the standard industrial 50Hz realm. Mind you 2x voltage and Tmax 3 =6 all up would be fine for now.
..in 2 pole or 4 pole ! as long as the revs suit !
iMiEV, 61,052km in pure Electric and loving it !
Back to Top
vince View Drop Down
Groupie
Groupie


Joined: 31 May 2008
Location: On.Canada
Status: Offline
Points: 173
Post Options Post Options   Thanks (0) Thanks(0)   Quote vince Quote  Post ReplyReply Direct Link To This Post Posted: 16 September 2009 at 12:31am
Thanks for getting back to me Woody,Tuarn always a pleasure.
Back to Top
bga View Drop Down
Senior Member
Senior Member
Avatar

Joined: 01 September 2008
Location: Perth WA
Status: Offline
Points: 493
Post Options Post Options   Thanks (0) Thanks(0)   Quote bga Quote  Post ReplyReply Direct Link To This Post Posted: 16 September 2009 at 11:55am
Lowering the winding voltage is fine until the controller runs out of current or di/dt capability. Some series inductance may be needed so that the controller stays happy. (big wires in big, heavy, toroids)

I wonder if there are differences in 2pole and 4pole rotors, because of the different field. I don't recall reading about this ever.

Also, rotors are usually a compromise with slip so that DOL starting works. For VFD applications the stall (and large slip rate) properties are hopefully irrelevant, allowing slip and peak torque to be optimised. I would think that this would affect the rotor construction, such as deep vs shallow bars, the helix angle, bar size or number of bars.

Any thoughts?
Back to Top
 Post Reply Post Reply Page  <123>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 10.18
Copyright ©2001-2014 Web Wiz Ltd.

This page was generated in 0.297 seconds.